An investigation into voter fraud in Colorado uncovered more than a dozen cases of people voting twice.

CBS4 in Denver discovered six new cases of the same people voting twice in elections, while in another six cases, people are suspected of voting in Colorado and in another state during the same election cycle.

It said that Lincoln Wilson, a Republican from Hale, Colo., voted in both Colorado and Kansas in 2014, 2012, and in 2010. He told CBS that he “voted on local issues” and “didn’t vote twice for President.”

In another case, Ron Weems, a registered Democrat, pleaded guilty to voting in Teller County, Colorado as well as in Kansas in both 2012 and 2014.

“You’d be surprised how often people double vote,” Kansas Secretary of State Kris Kobach told CBS. “Two of the cases are serial double voters. I think people discover they can get away with it and keep doing it.”

But Colorado Secretary of State Wayne Williams said there are a relatively small number of people who voted twice. “It’s a relatively small number,” said Williams. “But, it is a problem of any magnitude because we have close elections in Colorado.”

Williams noted that in some cases, people can show up twice in Colorado’s voter rolls if their information is slightly different, including a change of address or a change of name via marriage—or a typo.

The reports come as GOP presidential candidate Donald Trump raised suspicions on Thursday about the voting machines in reliably Republican Texas despite producing no evidence of an actual problem.

“A lot of call-ins about vote flipping at the voting booths in Texas. People are not happy. BIG lines. What is going on?” Trump said in a message to his followers on Twitter.

But Texas Secretary of State Carlos Cascos, a Republican, said on Facebook that there was no evidence of vote-flipping, a term generally used to describe a technical glitch on older electronic voting machines. Cascos’ spokeswoman said he was responding to speculation circulating on social media.

“Our office has received reports concerning rumors that some voting machines may be changing candidate selections when voters cast straight party ballots,” Cascos said in his statement, which was posted a day before Trump sent his Twitter message. “We are actively monitoring the situation, and have yet to receive any verified reports of machines changing votes.”